Hot Tip:

Work with a cool engine

Performance Gain:

Quiet power steering pump

Complementary Modification:

Power steering hoses

The steering system used in BMW Z4's is known as power-assisted rack-and-pinion steering. Rotating the steering wheel spins a small pinion gear, thus sliding a toothed rack left or right. The ends of the rack attach to tie-rods, which steer the front wheels. A hydraulic pump, powered by the engine accessory belt, forces steering fluid into hoses that leads to pistons in the steering rack. A hydraulic valve in the steering rack varies the hydraulic fluid pressure in the two cylinders, dependent on how fast or forcefully the pinion gear is rotated. This multiplies the driver's force in steering the wheels.

The power steering pump cooling loop helps to keep the fluid cool during operation. The loop in mounted in front of the A/C condenser and is susceptible to damage and corrosion. If you have what looks like a power steering fluid leak at the front of your vehicle, inspect the cooling loop first.

In this article, I'll go over the steps involved with replacing the power steering cooling loop and bleeding the power steering pump.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

The first step is to suction the fluid out of the reservoir. You can use a fluid pump or a turkey baster.

The power steering pump cooling loop helps to keep the fluid cool during operation. The loop in mounted in front of the A/C condenser (green arrow) and is susceptible to damage and corrosion. If you have what looks like a power steering fluid leak at the front of your vehicle, inspect the cooling loop first.

You can access the hoses (red arrow) from the engine compartment. Start by removing the intake air housing. See our tech article on intake air housing and ducts removing. Press the gray collar toward the hose (green arrow) and hold it while pulling the hose straight off the cooler line. Remove the hose from the mounting brackets, and install the new hose.

Push the condenser toward the engine. Expose the left side of the cooling loop, where it mounts to the bracket. Unclip the retainer (green arrow), and pull the cooling loop (red arrow) out of the plastic mount. You may have to wiggle it a bit to get it to free up.

When installing, be sure that the condenser tab (green arrow) is correctly seated in the plastic holder (red arrow). The photo shows the condenser viewed from above. Reverse the steps to reassemble the vehicle. Before starting the engine, fill the power steering reservoir with clean fluid to the MAX level on the dipstick. Start the engine and turn the steering wheel fully left and right three times. Turn the engine off. Check the fluid level. Add fluid until it reaches MAX on the dipstick. When full, the fluid should be clear and foam free. Foam or bubbles is a sign of air in the system.